مقایسه تراکم عناصر گروه پلاتین در کرومیتیت‌های افیولیت خوی: نشانه‌ای از حضور دو نوع کرومیتیت با دو خاستگاه متفاوت

Khoy ophiolitic complex in northwest of Iran have several chromitite bodies with various textures, different geochemical features and associated minerals. Based on Cr#, Khoy chromitites are divided into two groups: high-Cr (Cr# > 0.6) and high-Al (Cr# < 0.6) chromitites. The high-Cr contain some amount of PGEs with tiny grains of platinum-group minerals (PGM), whereas, high-Al chromitites are poor in PGE with no PGM inclusions. Geochemical analysis and Raman spectroscopy data on PGM inclusions in the high-Cr chromian spinels shows that they are laurite and rarely irarsite in composition. The PGE concentration in high-Cr- and high-Al chromitite reveals that the high-Cr chromitites probably were formed in a magmatic arc tectonic setting and those of high-Al were occurred in a back arc basin environment.